Use an electric mixer to blend together all the crepe ingredients except the butter for the pan in a large bowl. Blend just until smooth. The batter will be very thin.
Combine the filling ingredients in a medium bowl and mix by hand. Keep; the filling nearby.
Preheat a 10" frying pan over medium heat. (This size pan tapers to about 8" at the bottom.) When the pan is hot, add about 1/2 teaspoon of butter.
When the butter has melted, pour 1/3 cup of batter into the pan. Swirl the batter so that it entirely coats the bottom of the pan. Cook for 1-1/2 to 2 minutes or until golden brown on one side.
Use a spatula to lift an edge of the crepe. Grab it with your finger, slip the spatula underneath, and quickly flip it over. Cook for another 1-1/2 minutes or until a bit lighter shade of brown than the first side, then slide it out of the pan. Repeat with the rest of the batter, and stack the finished crepes on top of each other to keep them warm.
Heat the cheese filling in the microwave for 1 to 2 minutes or until it is hot.
When ready to fill the crepes, place each crepe, dark side down, on a plate. Pour 2 to 3 tablespoons of cheese filling across the center of the crepe. Fold the sides in and turn the entire blintz over (to hide the seam) onto a serving plate. You can use a knife to cut the rounded edges off the blintzes if you like. Repeat with remaining blintzes.
Serve 2 to 3 blintzes on a plate with a dollop of sour cream and two dollops of strawberry preserves carefully arranged on the plate next to the blintzes. Sprinkle the blintzes with powdered sugar.
Makes: 8